Fibromyalgia (FM) is a debilitating pain syndrome of unknown origin. Exercise improves pain, fatigue, and functioning in FM. Nevertheless, many barriers (e.g., pain, fatigue) prevent people with FM from exercising. Thus finding new ways to increase their physical activity is important. Since accumulating 30 minutes of moderate-intensity lifestyle physical activity (LPA), above usual activity, throughout the day (e.g., increase walking and decrease reliance on labor-saving devices) produces similar health benefits to exercise, the U.S. Surgeon General recommends LPA. We do not know, however, whether accumulating LPA would benefit people with FM. Based on pilot data we posit that accumulating moderate-intensity LPA will improve the major symptoms of FM. In this amended application, we propose a randomized controlled trial to evaluate the short- and moderate term effects of LPA on pain (the primary outcome), fatigue, tenderness, physical performance, physical activity, and functional capacity (secondary outcomes): As suggested by reviewers, we will also test potential mechanisms (i.e., pain perception, metabolic efficiency and perceived exertion, sleep parameters, pain catastrophizing) by which LPA might influence FM symptoms. To accomplish this, 160 sedentary adults with FM will be randomized to either LPA or a fibromyalgia education control (FME). LPA participants will be treated for 12 weeks and accumulate 30 minutes of moderate-intensity LPA, above usual activity, 5 to 7 days per week. FME participants will attend a monthly 2-hour meeting for 3 months where they will receive FM education, increased attention, and social support. Testing will occur at baseline, after the intervention, and at 6- and 12-month follow-up. The proposed study will enable us to determine if pain, fatigue, and function improve from participating in moderate-intensity LPA. Evaluating the effects of LPA on pain threshold, metabolic efficiency/perceived exertion, sleep parameters, and pain catastrophizing will provide mechanistic insight on how LPA influences the major symptoms of FM.